Two sea-going vessels carrying old bouncer (11)
I believe the answer is:
trampoliner
'two sea-going vessels carrying old' is the definition.
I can't tell whether this defines the answer.
'bouncer' is the wordplay.
I cannot really see how this works, but
'bouncer' could be 'trampoline' (I've seen this before) and 'trampoline' is found in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
(Another definition for trampoliner that I've seen is " Gymnast on apparatus".)